Fluorescence observation methods in which a sample is observed by irradiating the sample with an excitation light and detecting fluorescence emitted from the sample have been known as methods for observing a biological sample. Among them, the confocal fluorescence observation method which is a type of fluorescence observation method has been known as a method by which a fluorescence image that has a higher contrast and resolution compared with those with a normal fluorescence observation method may be obtained.
In the confocal fluorescence observation, an image of a sample is obtained by scanning the sample using a scanning unit. A mirror-type scanning unit such as a galvanomirror and a disk-type scanning unit such as a Nipkow disk are popular scanning unit used for the confocal fluorescence observation.
Disk-type scanning unit is disclosed in Japanese Laid-open Patent Publication No. 2013-054102, for example. While this is not particularly mentioned in Japanese Laid-open Patent Publication No. 2013-054102, a disk-type scanning unit and a relay optical system that performs relaying of an optical image of a sample to an imaging apparatus may be provided as a single unit (hereinafter referred to as a disk scanning apparatus) to being incorporated into a microscope apparatus.